Smartphones and other digital mobile devices in current use have on-board cameras for enabling a user to take photographs or videos and send them in communications to others. Prior camera lens adapters or couplers typically are formed in the shape of a bracket or casing for holding the camera lens of a smartphone or other camera-bearing device to the eyepiece of an optical instrument. However, these prior adapters or couplers do not provide a convenient way to align the horizon for the camera-bearing device with the horizon of a subject to be photographed or videoed through the optical instrument. Consequently, a user must take time to view a subject image through the camera-bearing device while coupled to the optical instrument and manually adjust the orientation of the camera-bearing device with the optical instrument until the viewed image is aligned with the horizon of the camera.